Control valve for the flow to and from a variable pressure chamber

ABSTRACT

A control valve has two valve pistons disposed on opposite sides of a straight passage which is connected at one end with an expanding and contracting pressure chamber of a hydraulic press or brake system, and has a discharge opening at the other end. The valve pistons have a first position in which fluid from the contracting pressure chamber can flow with minimal resistance through the straight passage and out of the discharge opening. In a second position of the valve pistons, the discharge opening is closed by the same, and pressure fluid can be supplied from an inlet through control valves into the straight passage and from there to the expanding pressure chamber.

United States Patent Herion et a].

AND FROM A VARIABLE PRESSURE I, CHAMBER.

inventors: Erich Herion, Stuttgart; Erich Ruchser, Stetten/Remstal, bothof Germany, Assignee: Technomatic AG, Aesch/Luzern,

Switzerland 7 Filed: Dec. 31, 1970 Appl. No.: 103,222

Foreign Application Priority Data Oct. 24, 1972 3,139,109 6/1964 Ruchser..91/424 905,585 '9/1962 Great Britain ..l37/l02 Primary Examiner-EdgarW. Geo ghegan Assistant Examiner-'Barry Gros'sman Attorney-Michael S.Striker [57] ABSTRACT A control valve has two valve pistons disposed onop- May 6, 1970 Switzerland"; .26935/ I June 30 1970 Switzerland.9953/70 Passage whch at one end wlth an expandmg and contractingpressure chamber of a hydraulic press or brake system, and has U.S. Cl...137/l02, 91/424, 9911/2362; 7 a discharge opening at the other end Thevalve Int Cl Gosd 7/00 Flsb 11/08 pistons have a first position in whichfluid from the Fie'ld H07 102 51/424 442 contracting pressure chambercan flow with minimal g 1 resistance through the straight passage andout of the discharge opening. In a second position of the valveReferences Cited pistons, the discharge opening is closed by the same, Iand pressurev fluid can be supplied from an inlet UNITED TES TE Sthrough control valves into the straight passage and 3 419 30 0/ 96 G tn /1 from thereto the expanding W' chamberra mu er 12/ 1920 Stage",..91/468 22 Claims, 12 Drawing Figures H v ii;= Hi": H

a0 86 as 0 62 90 PATENTEU 24 I973 3,6 99 .993

SHEU 2 OF 7 FIG. 4

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SHEET 5 OF 7 mmvmz PATENTEDHBI 24 I972 FIG. 77 56 SHEET 7 (IF .7

" INVENTOR.

emu flew/0m Ema Bum- 5L CONTROL VALVE FOR THE FLOW TO AND FROM AVARIABLE PRESSURE CHAMBER I BACKGROUND OF THE INVENTION trol positionretracted fromthe straight passage so that fluid from the pressurechamber flows through the straight passage and directly out of thedischarge opening, and a second control position located in the movabletoward and away from each other. The valve pistons have closure piecesprovided with longitudinal and transverse bores, through which apressure fluid is supplied to'a consumer apparatus after severaldeflections If this known control valve is shifted from the operativeposition to the inoperative position, the pres.- sure fluid flows fromthe pressure chamber in the consumer apparatus through the control valvealong a tortuous path on which it is several times deflected.

Due to the repeated deflection of the flows of fluid, delays occurduring the shifting of the control valve between the two controlpositions in which fluid is supplied to, or discharged from the pressurechamber of the consumer apparatus.

Modern machines operate at very high frequencies of the strokes, whichrequires short shifting periods for the control valve, and shorterperiods of time for filling and discharging the pressure chamber.

SUMMARY OF THE INVENTION It is one object of the invention to provide acontrol valve which requiresless time for shifting, and shorter fillingand discharge periods than control valves of the of aconsumer apparatus,and a return and discharge opening. In accordance with the invention,valve piston means are provided which close the discharge opening of thestraight passage while fluid is supplied into the passage and throughthe same to the pressure chamber of the consumer apparatus.

Due to the straight connection between the return and discharge openingand the connection with the expansible and contractable pressure chamberof the consumer apparatus, such as a hydraulic pressure, very shortfilling and emptying periods are obtained, which is due to the fact thatthe direction of flow of the pressure fluid need not be changed, alsodue to the fact that straight passage and closing the discharge opening.

The valve pistons are moved by pressure fluid in the supply conduitmeans and in the working cylinders to the second control position sothat the discharge opening is closed, and pressure fluid flows throughthe channel means into the straight passage and out of the same into thepressure chamber of the consumer apparatus for expanding the same. l I

In the preferred embodiment of the invention, two oppositelyv arrangedvalve pistons have confronting inner frustoconical end portionscooperating with corresponding frustoconical valve seats. Each of thevalve seats has a slot, and the slots are respectively closed by the twovalve pistons in the second control position.

, It is preferred to provide a channel in the valve pistons throughwhich pressure fluid is guided into the straight passage. A springbetween the valve pistons urges the same apart to the first controlposition. It is advantageous to provide check valves in the channels ofthe valve pistons, so that the valve pistons close the discharge openingof the straight passage, before the check valves open and the pressurefluid can flow through the straight passage into the pressure chamber ofthe consumer apparatus.

When a very large volume is required, it is advantageous to provide avalve for directly connecting the fluid inlet conduit with'the straightpassage.

In a preferred embodiment of the invention, each valve piston has itsouter peripheral surface, at least one channel recess which is directlyconnected with the inlet conduit for the pressure fluid, and throughwhich the pressure fluid can flow into the straight passage when thevalve pistons are placed in the second control position closing-thedischarge opening. In such an arrangement, even a very great volume ofpressure chamber, does not require an additional direct connection by avalve between the fluid inlet conduit and the the pressure fluid is notdeflected during flow through a supplying the pressure fluid into theworking cylinders.

Channel means connect'the supplyconduit means with the passage portionsof the passage. Valve pistons are located in the working cylinders formovement toward and away from the straight passage between a firstconstraight passage. v It is advantageous to make the diameters of thepiston parts outwardly of the channel recesses greater than the diameterof the piston parts located inward of the channel recesses, so that thepistons are urged outwardly to the first control position opening thedischarge opening.

A further feature of the invention is to provide a double piston in apressure cylinder forming balancing chambers at the ends of the pressurecylinder which are connected by first ducts with supply conduits for thefluid, and by second ducts with the straight passage. In such anarrangement, the double piston is operated to move to one of its endpositions and to actuate a stop motion switch for the consumerapparatus, if one of the control valves for controlling the flow ofpressure fluid to the channels of the valve pistons does notproperlyfunction, or if one of the valve pistons is blocked.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following BRIEF DESCRIPTION OF THE DRAWINGFIG. 1 is a schematic sectional view illustrating a first embodiment ofthe invention in a first control position;

FIG. 2 is a fragmentary schematic sectional view taken on line Il-II inFIG. 1;

FIG. 3 is a schematic sectional view illustrating the embodiment of FIG.1 in a second control position;

FIG. 4 is a fragmentary schematic sectional view taken on line IV-IV inFIG. 3;

FIG. 5 is a schematic section illustrating the embodiment of FIG. 1 inundesired condition caused by a malfunction;

FIG. 6 is a fragmentary cross section taken on line VI-VI in FIG. 5;

FIG. 7 is a schematic section illustrating a modification of theembodiment of FIG. 6 in a first control positron;

FIG. 8 is a schematic sectional view of he embodiment of FIG. 7 in asecond control position;

FIG. 9 is a schematic sectional view illustrating another embodiment ofthe invention in a first control position;

FIG. 10 is a fragmentary cross sectional view taken on line X-X inFIG.9;

FIG. 11 is a schematic sectional view of the embodiment of- FIG. 9 is asecond control position; and

FIG. 12 is a fragmentary sectional view taken on line XII-XII in FIG.11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 to4, a control valve 10 has a housing 12 in which two valve pistons 14 and16 are movably mounted in working cylinders 15 and 17. The two pistons14 and 16 are coaxial, and movable toward and away from each other. Theconfronting inner end portions 18 and 20 of the two pistons 14 and 16are frustoconical, and cooperate with corresponding frustoconical valveseats 22 and 24. The working cylinders l5 and 17 are connected at theinner ends thereof by a passage portion.25. Valve pistons 14 and 16 aresealed in working cylinders 15 and 17 by sealing rings 14a and 160. Eachof the pistons 14 and 16 has a cen-. tral axially extending channel orbore 26,28, respectively see FIG. 2, to which pressure fluid is suppliedfrom supply channels 72 and 74 communicating through supply conduits 64and 66 with an inlet conduit 62. A compression spring 30 is mounted inthe aligned bores 26 and 28, and has outer ends abuting shoulders 32 and34 provided in bores 26 and 28. Spring 30 urges the two valve pistons 14and 16 apart. A check valve 36 and 38, respectively, is provided in eachbore 26 and 28.

As shown in FIGS. 2 and 4, a passage 44 has an opening 40 at one endwhich is connected with the expanding and contracting pressure chamberof a hydraulic press, not shown, and has a discharge opening 42 at theother end thereof so that a pressure fluid discharged by the contractingpressure chamber of the hydraulic press can flow through passage 44 andout of discharge opening 42'without pressure loss. In accordance withthe invention, the passage 44 between the openings 40 and 42 is straightso that fluid flowing into opening 40,

through passage 44 and out of discharge opening 42, is not deflected,and consequently encounters very little flow resistance.

The straight passage .44 has two portions 45 and 47,

of which the portion 45 is connected with the pressure chamber of thehydraulic press, and portion 47 is connected with the return conduit.The portion 45 is connected by a single opening 46 with the centralspace 49 from which a pressure fluid supplied through channels 26 and 28can flow through portion 45 of passage 44 to the consumer apparatus, orthrough the discharge opening in portion 47 to the return conduit. Theportion 47 of the straight passage 40 communicates with the centralspace 49 through two discharge slots 48 and 50 which are separated by apartition body 52, as best seen in FIGS. 2 and 4.

The dischargeslots 48 and 50 have openings in the valveseats 22 and 24of the valves 76 and 78, each of which includes one of the valve pistons14 and 16, and the respective valve seats 22 and 24. The workingchambers 77 and 79 of valves 76 and 78 are connected by supply conduits72 and 74 with control valves 54 and 56 which have valve seats 58,68,and 60,70, respectively. The valve seats 58 and 60 of the, two controlvalves 54 and 56 are connected by supply conduits 64 and 66 with theinlet conduit 62 to which pressure fluid is supplied in the direction ofthe arrow P. A pump, not shown, may be connected with the inlet conduit62. The valve pistons 68 and 70 of the control valves 54 and 56 are, forexample, electromagnetically operated. Control valve 56 controls valve78, and control valve 54 controls valve 76. The control valve device 10is provided with a stop motion arrangement for stopping the consumerapparatus, such as a hydraulic press, when a malfunction takes place. Apressure balancing device is provided for this purpose, and includes adouble piston 82 movable in a pressure cylinder 83 in housing 12. Theend faces 84 and 86 of the double piston 82 form balancing chambers and87 which-are connected by ducts 92 and 94 with the supply conduits 72and 74 which connect the control valves 56,54 with the working chambers77 and 79, and also connected by ducts 96 and 98 with the spaces 97and99 in front of valve pistons 14' and 16. As shown in FIGS. 1 and 3,ducts 96 and 98 open at the valve seats 22 and 24.

Check valves 100 and 102 are provided in the ducts 92 and 94, togetherwith throttles 103 and 105. Double piston 82 has slanted actuating faces104 and 106 which control the actuator ofa stop motion switch 110.

The control valve device 10 shown in FIGS. 1 to 4 operates as follows:

In the position of FIG. 1, the two control valves 54 and 56 are closed,and pressure fluid cannot flow through conduits 62, 64, 66 and valveseats 58 and 60. Neither valves 76 and 78, nor the stop motion device 80are subjected to fluid pressure. Double piston 82 is in a centralposition due to the action of springs 88 and 90. Stop motion switch 110is open. Valve pistons 14 and 16 are in the retracted outer positionsand the pressure chamber of the consumer apparatus, not shown, is

connected with the opening 40 and through the straight When the twocontrol valves 54 and 56 are simultaneously actuated by electromagneticmeans, they assume the position shown in FIG. 3, and the two reliefopenings 68 and 70 are'closed, while the valve seat openings 58 and 60are opened. The pressure fluid and 38 in channels 26 and 28 of pistons-16 and 14 permit the building up of pressure in the working chambers 77and 79 before opening the channels 26 and 28 forthe flow of pressurefluid from the working chambers into the straight passage 44. Thepistons 14 and 16 move towards each other until they abut on the valveseats 22 and 24, and close in this controlposition, the discharge slots48 and 50 which communicate with the discharge opening 42 of the returnconduit. The check valves 36 and 38 open so that the pressure fluidflows into the central space 49 and out of opening 46 into the endportion 45 of the straight passage 44 which is connected with thepressure chamber of the consumer apparatus.

The end faces 84 and 86 of the safety device 80 are subjected to equalpressure of the pressure fluid which flows through ducts 92 and 94.Ducts 96 and 98 which open in the valves seats are closed by the valvevpistons 14 and 16 in the inner control position. Consequently,

the double piston 82 remains in the central position. so that stopmotion switch 110 is not actuated.

FIGS. 5 and 6 illustrate a malfunction of. the device. It is assumedthat upon shifting of control valves 54 and 56 by electromagnetic means,only the controlvalve 54 opens, as control valve 56, perhaps due tofailure of the electromagnetic means, has remained in the inoperativeposition closing opening 60.

Piston 14 is subjected to pressure and moves towards its valve seat,while piston 16 remains in the outer inoperative position. Dischargeslot 50 is closed by piston 14, while discharge slot 48'remains open.The pressure fluid flows through control valve 54 and opening 58 intothe working chamber 77 and through the respective check valve 38 and thecorresponding channel 26 and the open discharge slot 48 directly tothereturn conduit. The ratio between the flow across sections of thecontrol valves 54 and 56 and the channel 26 is about 1:10 so that in theinterior of the valve, only a small pressure remains which is below thepressure required by the pressure chamber of the .consumer apparatus,such as a coupling or a brake of a press. Consequently, no pressurefluid is supplied to the consumer apparatus.

Due to the one-sided pressure in the balancing chamber 85, whichis notopposed by an equivalent pressure in the balancing chamber '87 due tothe fact that the control valve 56 has not operated, double piston 82moves to the leftas viewed in FIG. 5 so that the slanted face 106operates the actuator pin of the stop motion switch 110 whichdisconnects to a relay, not shown, the main switchof the press which isthus stopped.

The position of the control valve device shown in FIGS. 5 and 6alsoresults in the event that both control valves .54 and 56 are correctlyoperated, but valve piston16 is blocked in this outer position. Thepressure fluid flows through the channels in the valve pistons 14 and16, and then flows through the open discharge slot 48 into thexreturnconduit. The pressure fluid further flowsthrough duct 92 and duct 94towards the balancing chambers 87 and 85. While duct 96 is closed byvalve piston 14- so that pressure can develop in the balancing chamber85, 1duct98 is open since valve piston 16 has not moved-forward to theinner control position. The fluid flowing through duct 94 con} sequentlyflows through duct 98 into the space97' in front of valve piston'16, andout of discharge slot 48. No pressure can develop in balancing chamber87 so that the double piston 82 moves to the left and operates the stopmotion switch 10.

The same condition of the device is obtained when the control valves 54and 56 are shifted out of the position shown in FIG. 3 to the positionof FIG. 1, while valve piston. 14 is blocked in the inner controlposition shown in FIG. 5. Valve piston 16 is moved to the outer controlposition by the action of spring 30, so that discharge slot 48 leadingto the return conduit, and also the opening of the duct 98 which isconnected with balancing chamber 87 is uncovered. The pressure chamberof the consumer apparatus is relieved since the straight passage 44 tothe discharge opening 42 is opened. In the same manner, the balancingchamber 87 is relievedsince the pressure fluid flows away through duct98. It is not possible for the pressure fluid to flow out of thebalancing chamber 85, since the check valve 100 prevents relief throughthe control valves 54,56, andduct 96 is closed by the blocked valvepiston 14. The endface 84 of the double piston 82 is subjected to fluidpressure, while the end face 86 is relieved. Due to the pressuredifferential, the double piston 82 moves out 'of the'central position asshown in FIG. 3 to the left, so that stop motion switch is operated.

Preferably, throttles 103 and 105 are provided .in ducts 92 and 94 inorder to equalize small motion and shifting tolerances of the valves,and also for obtaining a uniform pressure built up in the safety device80. For the same reason, double piston 82 may be provided with athrottle connecting the two end faces.

A modified embodiment of the invention illustrated in FIGS. 7 and 8corresponds to the embodiments of FIGS. 1 to 6, but has a differentchannel arrangement for connecting the inlet conduit 82 with thestraight passage 44.

For large volumes, the flow cross section of the control valves 54, 56is insufficient for a large pressure chamberof the brake or clutch ofthe consumer apparatus, and therefore a large valve means with a largercross section is provided in housing 12, and is operated .by anactuating piston 124. Valve 120 is connected by a channel 122 with theinlet conduit 62. The auxiliary piston 124 is connected by a piston rod125 with valve 120, and is controlled by control valve 54 through achannel 126. In the open position of valve .120 shown in FIG. 8,pressure fluid from inlet conduit 62 flows through valve seat 128 and aconnecting chan- .nel 130 directly into the portion 45 of the straightpassage 44 which is connected with the consumer apparatus, as explainedwith reference to FIG. 2. Due to the direct connection between theinlet-conduit 62 and the straight passage 44, it is not necessary tosupply fluid through supply conduits 72 and 74 and channels 26,28 inpistons 14 and 16, as described with reference to FIGS. 1 and 2.Insteadof the channels 26 and 28, corresponding blind bores are provided inpistons 14 and 16 in which spring- 30 is located for urging the pistonsaway from each other.

In the event that the valve 120 malfunctions and, for example, remainsin the closed position as shown in FIG. 7, no fluid is supplied to theconsumer apparatus. In the event that the valve 120 remains in its openposition after the control valves 54 and 56 have been shifted, perhapsdue to jamming of piston 124, the supplied pressure fluid flows throughthe discharge slots 48 and 50 which are opened by the retracted pistons14 and 16. Consequently, a single valve 120 is sufficient.

In the embodiment illustrated in FIGS. 9 to 12, each of the two valvepistons 14'.and 16 has four channel recesses 140 and 142, respectively,which extend parallel to the axis of symmetry of the respective pistonand over a part of its axial length. The channel recesses 140 and 142,respectively, are spaced 90 in circumferential direction, and the bottomof the channel recesses 140,142 is preferably part-circular so that thechannel recesses 140,142 are substantially segment shaped, as shown inthe drawing.

The channel recesses form part of the channel means by which the inletconduit 62 is connected with the straight passage 44 when the valvepiston 14' and 16 are in the inner control position shown in FIG. 12.The channel recesses, and associated channels, replace the channel bores26 and 28 of the embodiment of FIGS. 1 to 4 In the position of thecontrol valve device shown in FIGS. 9 and 10, the control valves 54 and56 are closed. The channel recesses 140 and 142 register with openings160 and 162 and annular channels 161,163 in housing 12, and are furtherconnected by supply conduits64 and 66 with an inlet conduit 62 throughwhich the pressure fluid is supplied. Sealing means 156 and 158 inhousing 12 prevent in the position of FIG. 9, the flow of pressure fluidfrom channel recesses 140,142 into the straight passage 44. Sealingmeans 156 and 158 cooperate with portions 148 and 150 of the valvepistons 14' and 16'. Sealing means 152,154 seal the channel recesses140,142 from the separate conduits 72 and 74 which are supplied withfluid when the control valves 54 and 56 are operated. Sealing rings152,154 are mounted in annular portions 144 and 146 of the valve pistons14' and 16'.

When the control valves 54 and 56 are moved to the position of FIG. 11,pressure fluid flows through valve seats 60 and 58 into the supplyconduits 72 and 74 and exerts pressure on the outer end faces of valvepistons 14' and 16' so that the valve pistons move to the inner controlposition closing the discharge slots 48 and 50 which communicate withthe discharge opening 42.

The channel recesses 140,142 are in this control position not any moresealed from the straight passage 44. The pressure fluid flows throughinlet conduit 62, supply conduit 64 and 66, openings 160 and 162, andannular channels 161 and 163 into the channel recess 140.142 and out ofthe same through annular gaps 164,166, see FIG. 12, so that the fluidenters the straight passage 44 and flows to the consumer ap'- paratus.Annularchannels 168,170, see FIG. 12, are provided in housing 12 throughwhich the pressure fluid flowing out of annular gaps 164 and 166 isguided to the opening 40 communicating with consumer apparatus. Y

As is apparent from the drawing, the diameter of the piston portions154,156 which are located outwardly of the channel recesses 140,142 isgreater than the diameter of the portions 148,150 which are locatedinwardly of the channel recesses 140,142. In this manner, a pressuredifferential is obtained which urges the. valve pistons14' and 16' outofthe control position shown in FIG. 9. The embodiments of FIGS. 9 to 12is particularly advantageous since it. is suitable for very high volumesof the pressure chamber'of theconsumer apparatus without requiring valve120 of the embodiment of FIGS. 7 and 8.

The spring by which the fluid is pressed out of the working chambers ofvalve pistons 14 and 16' in the embodiments of FIGS. 1 to 8, can be sodesigned that it permits a closing of the straight passage 40 by thevalve pistons only at a predetermined pressure, for example more than 3k/cm. Such an arrangement eliminates the necessity of providing apressure operated switch responsive to the pressure of the fluid.

More than one safety device may be provided for operating other switcheswhen a malfunction takes place. It is advantageous to make the valvepistons of a synthetic plastic material so that the mass is small,permitting a further reduction of the time periods for acceleration ofthe pistons so that the time required for shifting the control valvedevice is further reduced.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofcontrol valve devices differing from the types described above.

While the invention has been illustrated and described as embodied in acontrol valve device including a straight passage for connecting thevariable pressure chamber of a consumer apparatus with a dischargeopening, it is not intended to be limited to the details shown, sincevarious modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptions should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

We claim:

1. Control valve for controlling the flow to and from a variablepressure chamber of a consumer apparatus, comprising housing meansincluding a substantially straight passage means connected at one endwith said pressure chamber, and having at the other end thereof adischarge opening, said housing means having working cylinder meanslaterally of said straight passage means, and supplyconduit meansincluding an inlet conduit for supplying a pressure fluid into saidworking cylinder means; channel means connecting said supply conduitmeans with apassage portion of said passage means; and valve pistonmeans located in said working cylinder means for movement toward andaway from said straight passage means between a first control positionretracted from said straight passage means so that fluid from saidpressure chamber flows through said straight passage means and directlyout of said discharge opening, and a second control position located insaid straight passage means and closing said discharge opening, saidvalve piston means being moved by pressure fluid in said supply conduitmeans and in said working cylinder means to said second control positionso that said discharge opening is closed, and pressure fluid flowsthrough said channel means into said passage portion and out of said oneend into said pressure chamber for expanding the same.

2. Control valve as claimed in claim 1,;wherein said working cylindermeans includes two working cylinders located on opposite sides of saidstraight passage means; wherein said valve piston means include twovalve pistons located in said working cylinders; wherein said supplyconduit means includes two supply conduits respectively connecting saidinlet conduit with said working cylinder; wherein said channel meansincludes two channels formed by said valve pistons, respectively, andcommunicating with said working cylinders, respectively; and whereinfluid pressure in said supply conduits and workingcylinders-simultaneously urges said valve pistons to said second controlposition for together closing said discharge opening while pressurefluid flows through said channels and straight passage means into saidpressure chamber.

3. Control valve as claimed in claim 2, wherein said working cylindersform frustoconical valve seats adjacent said straight passage means; andwherein said valve pistons have inner confronting frustoconical endportions abutting said frustoconical valve seats in said second controlposition. v

4.. Control valve as claimed in claim 3, wherein said straight passagemeans includes a partition body divide ing said discharge opening intotwo discharge slots; wherein said frustoconical end portions of saidvalve piston in said second control position abut said partition bodyand close said discharge slots.

5. Control valve as claimed in claim 4, wherein said work-ing cylindersare located outward of said valve pistons and receive the end portionsof said valve pistons remote from said frustoconical end portions.

6. Control valve as claimed in claim 4, wherein said frustoconical endportions have central end faces spaced from each other in said secondcontrol position and located in said passage portion; and wherein saidchannels extend axially of said frustoconical end portions in said valvepistons and open on said end faces for connecting said supply conduitswith said passage portion.

7. Control valve as claimed in claim 2 wherein said channel meansinclude axially extending bores in said valve pistons having partlyclosed outer ends; and a pressure spring located in said bores betweensaid partly closed ends, and urging said valve pistons apart to saidfirst control position.

8. Control valve as claimed in claim 2, wherein said channels'extendbetween the outer and inner ends of said valve pistons, respectively;and comprising biassed check valves located in said channels,respectively, and adapted to close said channels so that said valvepistons are moved to said second controlposition by the pressure in saidworking cylinders whereupon the pressure increases in said workingchambers and opens said check valves to permit flow through saidchannels into said passage means and out of 'said one end of the same.

9. Control valve as claimed in claim 2, comprising two control valvesmounted in said housing means operable between an operative positionopening said supply conduits, respectively, and an inoperative positionclosing the same so that the movements of said valve pistons arecontrolled by said control valves; and wherein the ratio between theeffective flow cross sections of said supply conduits controlled by saidcontrol pistons and said channels in said valve pistons is about 1:10.

10. Control valve as claimed in claim 1, comprising a valve meanslocated in said channel means and having a closed position, and an openposition for connecting said inlet conduit directly with said straightpassage means.

11. Control valve as claimed in claim 10, comprising control valve meansmounted on said housing means operable between an operative positionconnecting said inlet conduit with said working cylinder means, and .aninoperative position disconnecting the same; and comprising actuatingpiston and cylinder means for operating said valve means under thecontrol of said control valve means.

12. Control valve means as claimed in claim 1, wherein said workingcylinder means include two working cylinders located on opposite sidesof said straight passage means; wherein said valve piston means includetwo valve pistons located in said working cylinders, respectively;wherein said supply conduit means include two supply conduits connectingsaid inlet conduit with said working cylinders, respectively; andwherein said channel means include channel recesses in said valvepistons communicating with said inlet conduit and being closed in saidfirst control position,and communicating also with said straight passagemeans in said second control position.

13. Control valve as claimed in claim 12, wherein said valvepistonscomprise sealing rings engaging said working cylinders in said firstcontrol position for sealing said channel recesses against communicationwith said straight passage means.

14. Control valve as claimed in claim 12, wherein channel recessesinclude a plurality of channel recesses spaced circumferentially abouteach of said valve pistons.

15. Control valve as claimed in .claim 14, wherein said channel recessesextend in the respective valve piston parallel to the axis of symmetryof the same and over a part of the length of the same.

16. Control valve as claimed in claim 12, wherein each of said channelrecesses has a part-circular bottorn and is segment shaped.

17. Control valve as claimed in claim 12, wherein each valve piston hasa greater diameter at the outer end portion remote from said straightpassage means than at the inner end portion thereof; and wherein saidchannel recesses are located between said inner and outerend portions.

18. Control valve as claimed in claim 1, wherein said working cylindermeans include two working cylinders located on opposite sides of saidstraight passage means; wherein said valve piston means include twovalve pistons located in said working cylinders, respectively; whereinsaid supply conduit means include two supply conduits connecting saidinlet conduit with said working cylinders, respectively; wherein saidhousing means forms a pressure cylinder having ends; comprising a doublepiston in said pressure cylinder forming balancing chambers at said endsof said pressure cylinder and being movable between a centralinoperative position, and two end positions; a stop motion switchactuated by said double piston in said end positions; wherein saidhousing means has first ducts connecting said supply conduits with saidbalancing chambers, respectively, and second ducts connected with saidbalancing chambers, respectively, and communicating with said straightpassage means in said first control positions of said valve pistons, andbeing closed, respectively, by the respective valve piston in saidsecond control position of the same whereby malfunctions of any valvepiston causes movement of said double piston to one end position andactuation of said stop motion switch.

19. Control valve as claimed in claim 18, wherein 12 said valve pistonshave confronting inner ends; wherein said housing means include valveseats for said inner ends engaged by the same in said second controlposition; and wherein said second ducts open in said valve seats,respectively, and are closed by the respective valve piston in saidsecond control position of the same.

20. Control valve as claimed in claim 18, comprising check valves insaid first ducts for blocking flow from said balancing chambers intosaid supply conduits, respectively.

21. Control valve as claimed in claim 18, comprising throttle means insaid first ducts, respectively.

22. Control valve as claimed in claim 1 wherein said housing means has atop portion in which said one end of said straight passage means formsan opening communicating with said variable pressure chamber, and abottom portion in which the other end of said straight piston means arecontrolled by said control valve

1. Control valve for controlling the flow to and from a variablepressure chamber of a consumer apparatus, comprising housing meansincluding a substantially straight passage means connected at one endwith said pressure chamber, and having at the other end thereof adischarge opening, said housing means having working cylinder meanslaterally of said straight passage means, and supply conduit meansincluding an inlet conduit for supplying a pressure fluid into saidworking cylinder means; channel means connecting said supply conduitmeans with a passage portion of said passage means; and valve pistonmeans located in said working cylinder means for movement toward andaway from said straight passage means between a first control positionretracted from said straight passage means so that fluid from saidpressure chamber flows through said straight passage means and directlyout of said discharge opening, and a second control position located insaid straight passage means and closing said discharge opening, saidvalve piston means being moved by pressure fluid in said supply conduitmeans and in said working cylinder means to said second control positionso that said discharge opening is closed, and pressure fluid flowsthrough said channel means into said passage portion and out of said oneend into said pressure chamber for expanding the same.
 2. Control valveas claimed in claim 1, wherein said working cylinder means includes twoworking cylinders located on opposite sides of said straight passagemeans; wherein said valve piston means include two valve pistons locatedin said working cylinders; wherein said supply conduit means includestwo supply conduits respectively connecting said inlet conduit with saidworking cylinder; wherein said channel means includes two channelsformed by said valve pistons, respectively, and communicating with saidworking cylinders, respectively; and wherein fluid pressure in saidsupply conduits and working cylinders simultaneously urges said valvepistons to said second control position for together closing saiddischarge opening while pressure fluid flows through said channels andstraight passage means into said pressure chamber.
 3. Control valve asclaimed in claim 2, wherein said working cylinders form frustoconicalvalve seats adjacent said straight passage means; and wherein said valvepistons have inner confronting frustoconical end portions abutting saidfrustoconical valve seats in said second control position.
 4. Controlvalve as claimed in claim 3, wherein said straight passage meansincludes a partition body dividing said discharge opening into twodischarge slots; wherein said frustoconical end portions of said valvepiston in said second control position abut said partition body andclose said discharge slots.
 5. Control valve as claimed in claim 4,wherein said working cylinders are located outward of said valve pistonsand receive the end portions of said valve pistons remote from saidfrustoconical end portions.
 6. Control valve as claimed in claim 4,wherein said frustoconical end portions have central end faces spacedfrom each other in said second control position and located in saidpassage portion; and wherein said channels extend axially of saidfrustoconical end portions in said valve pistons and open on said endfaces for connecting said supply conduits with said passage portion. 7.Control valve as claimed in claim 2 wherein said channel means includeaxially extending bores in said valve pistons having partly closed outerends; and a pressure spring located in said bores between said partlyclosed ends, and urging said valve pistons apart to said first controlposition.
 8. Control valve as claimed in claim 2, wherein said channelsextend between the outer and inner ends of said valve pistons,respectively; and comprising biassed check valves located in saidchannels, respectively, and adapted to close said channels so that saidvalve pistons are moved to said second control position by the pressurein said working cylinders whereupon the pressure increases in saidworking chambers and opens said check valves to permit flow through saidchannels into said passage means and out of said one end of the same. 9.Control valve as claimed in claim 2, comprising two control valvesmounted in said housing means operable between an operative positionopening said supply conduits, respectively, and an inoperative positionclosing the same so that the movements of said Valve pistons arecontrolled by said control valves; and wherein the ratio between theeffective flow cross sections of said supply conduits controlled by saidcontrol pistons and said channels in said valve pistons is about 1:10.10. Control valve as claimed in claim 1, comprising a valve meanslocated in said channel means and having a closed position, and an openposition for connecting said inlet conduit directly with said straightpassage means.
 11. Control valve as claimed in claim 10, comprisingcontrol valve means mounted on said housing means operable between anoperative position connecting said inlet conduit with said workingcylinder means, and an inoperative position disconnecting the same; andcomprising actuating piston and cylinder means for operating said valvemeans under the control of said control valve means.
 12. Control valvemeans as claimed in claim 1, wherein said working cylinder means includetwo working cylinders located on opposite sides of said straight passagemeans; wherein said valve piston means include two valve pistons locatedin said working cylinders, respectively; wherein said supply conduitmeans include two supply conduits connecting said inlet conduit withsaid working cylinders, respectively; and wherein said channel meansinclude channel recesses in said valve pistons communicating with saidinlet conduit and being closed in said first control position, andcommunicating also with said straight passage means in said secondcontrol position.
 13. Control valve as claimed in claim 12, wherein saidvalve pistons comprise sealing rings engaging said working cylinders insaid first control position for sealing said channel recesses againstcommunication with said straight passage means.
 14. Control valve asclaimed in claim 12, wherein channel recesses include a plurality ofchannel recesses spaced circumferentially about each of said valvepistons.
 15. Control valve as claimed in claim 14, wherein said channelrecesses extend in the respective valve piston parallel to the axis ofsymmetry of the same and over a part of the length of the same. 16.Control valve as claimed in claim 12, wherein each of said channelrecesses has a part-circular bottom and is segment shaped.
 17. Controlvalve as claimed in claim 12, wherein each valve piston has a greaterdiameter at the outer end portion remote from said straight passagemeans than at the inner end portion thereof; and wherein said channelrecesses are located between said inner and outer end portions. 18.Control valve as claimed in claim 1, wherein said working cylinder meansinclude two working cylinders located on opposite sides of said straightpassage means; wherein said valve piston means include two valve pistonslocated in said working cylinders, respectively; wherein said supplyconduit means include two supply conduits connecting said inlet conduitwith said working cylinders, respectively; wherein said housing meansforms a pressure cylinder having ends; comprising a double piston insaid pressure cylinder forming balancing chambers at said ends of saidpressure cylinder and being movable between a central inoperativeposition, and two end positions; a stop motion switch actuated by saiddouble piston in said end positions; wherein said housing means hasfirst ducts connecting said supply conduits with said balancingchambers, respectively, and second ducts connected with said balancingchambers, respectively, and communicating with said straight passagemeans in said first control positions of said valve pistons, and beingclosed, respectively, by the respective valve piston in said secondcontrol position of the same whereby malfunctions of any valve pistoncauses movement of said double piston to one end position and actuationof said stop motion switch.
 19. Control valve as claimed in claim 18,wherein said valve pistons have confronting inner ends; wherein saidhousing means include valve seats for said inner ends engageD by thesame in said second control position; and wherein said second ducts openin said valve seats, respectively, and are closed by the respectivevalve piston in said second control position of the same.
 20. Controlvalve as claimed in claim 18, comprising check valves in said firstducts for blocking flow from said balancing chambers into said supplyconduits, respectively.
 21. Control valve as claimed in claim 18,comprising throttle means in said first ducts, respectively.
 22. Controlvalve as claimed in claim 1 wherein said housing means has a top portionin which said one end of said straight passage means forms an openingcommunicating with said variable pressure chamber, and a bottom portionin which the other end of said straight passage means forms saiddischarge opening; wherein said valve piston means are movable in adirection transverse to said straight passage means; and wherein saidsupply conduit means are located in a plane transverse to said straightpassage means; and further comprising control valve means mounted insaid housing means operable for opening and closing said supply conduitmeans so that the movements of said valve piston means are controlled bysaid control valve means.